Abstract
This study analyzed the regulation of α2-adrenoceptors (α2-ARs) in human vascular smooth muscle cells (VSMs). Saphenous veins and dermal arterioles or VSMs cultured from them expressed high levels of α2-ARs (α2C > α 2A, via RNase protection assay) and responded to α 2-AR stimulation [5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine (UK-14,304, 1 μM)] with constriction or calcium mobilization. In contrast, VSMs cultured from aorta did not express α2-ARs and neither cultured cells nor intact aorta responded to UK-14,304. Although α2-ARs (α2C ≫ α2A) were detected in aortas, α2C-ARs were localized by immunohistochemistry to VSMs of adventitial arterioles and not aortic media. In contrast with aortas, aortic arterioles constricted in response to α2-AR stimulation. Reporter constructs demonstrated higher activities for α2A- and α2C-AR gene promoters in arteriolar compared with aortic VSMs. In arteriolar VSMs, serum increased expression of α2C-AR mRNA and protein but decreased expression of α2A-ARs. Serum induction of α2C-ARs was reduced by inhibition of p38 mitogen-activated protein kinase (MAPK) with 2 μM SB-202190 or dominant-negative p38 MAPK. UK-14,304 (1 μM) caused calcium mobilization in control and serum-stimulated cells: in control VSMs, the response was inhibited by the α2A-AR antagonist BRL-44408 (100 nM) but not by the α2C-AR antagonist MK-912 (1 nM), whereas after serum stimulation, MK-912 (1 nM) but not BRL-44408 (100 nM) inhibited the response. These results demonstrate site-specific expression of α2-ARs in human VSMs that reflects differential activity of α2-AR gene promoters; namely, high expression and function in venous and arteriolar VSMs but no detectable expression or function in aortic VSMs. We found that α2C-ARs can be dramatically and selectively induced via a p38 MAPK-dependent pathway. Therefore, altered expression of α 2C-ARs may contribute to pathological changes in vascular function.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Heart and Circulatory Physiology |
| Volume | 286 |
| Issue number | 1 55-1 |
| State | Published - Jan 2004 |
| Externally published | Yes |
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Keywords
- BRL-44408
- Microcirculation
- MK-912
- p38 mitogen-activated protein kinase
ASJC Scopus subject areas
- Physiology
Cite this
Regulation of α2-adrenoceptors in human vascular smooth muscle cells. / Chotani, Maqsood A.; Mitra, Srabani; Su, Baogen Y.; Flavahan, Sheila; Eid, Ali H.; Clark, K. Reed; Montague, Christine R.; Paris, Hervé; Handy, Diane E.; Flavahan, Nicholas.
In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 286, No. 1 55-1, 01.2004.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Regulation of α2-adrenoceptors in human vascular smooth muscle cells
AU - Chotani, Maqsood A.
AU - Mitra, Srabani
AU - Su, Baogen Y.
AU - Flavahan, Sheila
AU - Eid, Ali H.
AU - Clark, K. Reed
AU - Montague, Christine R.
AU - Paris, Hervé
AU - Handy, Diane E.
AU - Flavahan, Nicholas
PY - 2004/1
Y1 - 2004/1
N2 - This study analyzed the regulation of α2-adrenoceptors (α2-ARs) in human vascular smooth muscle cells (VSMs). Saphenous veins and dermal arterioles or VSMs cultured from them expressed high levels of α2-ARs (α2C > α 2A, via RNase protection assay) and responded to α 2-AR stimulation [5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine (UK-14,304, 1 μM)] with constriction or calcium mobilization. In contrast, VSMs cultured from aorta did not express α2-ARs and neither cultured cells nor intact aorta responded to UK-14,304. Although α2-ARs (α2C ≫ α2A) were detected in aortas, α2C-ARs were localized by immunohistochemistry to VSMs of adventitial arterioles and not aortic media. In contrast with aortas, aortic arterioles constricted in response to α2-AR stimulation. Reporter constructs demonstrated higher activities for α2A- and α2C-AR gene promoters in arteriolar compared with aortic VSMs. In arteriolar VSMs, serum increased expression of α2C-AR mRNA and protein but decreased expression of α2A-ARs. Serum induction of α2C-ARs was reduced by inhibition of p38 mitogen-activated protein kinase (MAPK) with 2 μM SB-202190 or dominant-negative p38 MAPK. UK-14,304 (1 μM) caused calcium mobilization in control and serum-stimulated cells: in control VSMs, the response was inhibited by the α2A-AR antagonist BRL-44408 (100 nM) but not by the α2C-AR antagonist MK-912 (1 nM), whereas after serum stimulation, MK-912 (1 nM) but not BRL-44408 (100 nM) inhibited the response. These results demonstrate site-specific expression of α2-ARs in human VSMs that reflects differential activity of α2-AR gene promoters; namely, high expression and function in venous and arteriolar VSMs but no detectable expression or function in aortic VSMs. We found that α2C-ARs can be dramatically and selectively induced via a p38 MAPK-dependent pathway. Therefore, altered expression of α 2C-ARs may contribute to pathological changes in vascular function.
AB - This study analyzed the regulation of α2-adrenoceptors (α2-ARs) in human vascular smooth muscle cells (VSMs). Saphenous veins and dermal arterioles or VSMs cultured from them expressed high levels of α2-ARs (α2C > α 2A, via RNase protection assay) and responded to α 2-AR stimulation [5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine (UK-14,304, 1 μM)] with constriction or calcium mobilization. In contrast, VSMs cultured from aorta did not express α2-ARs and neither cultured cells nor intact aorta responded to UK-14,304. Although α2-ARs (α2C ≫ α2A) were detected in aortas, α2C-ARs were localized by immunohistochemistry to VSMs of adventitial arterioles and not aortic media. In contrast with aortas, aortic arterioles constricted in response to α2-AR stimulation. Reporter constructs demonstrated higher activities for α2A- and α2C-AR gene promoters in arteriolar compared with aortic VSMs. In arteriolar VSMs, serum increased expression of α2C-AR mRNA and protein but decreased expression of α2A-ARs. Serum induction of α2C-ARs was reduced by inhibition of p38 mitogen-activated protein kinase (MAPK) with 2 μM SB-202190 or dominant-negative p38 MAPK. UK-14,304 (1 μM) caused calcium mobilization in control and serum-stimulated cells: in control VSMs, the response was inhibited by the α2A-AR antagonist BRL-44408 (100 nM) but not by the α2C-AR antagonist MK-912 (1 nM), whereas after serum stimulation, MK-912 (1 nM) but not BRL-44408 (100 nM) inhibited the response. These results demonstrate site-specific expression of α2-ARs in human VSMs that reflects differential activity of α2-AR gene promoters; namely, high expression and function in venous and arteriolar VSMs but no detectable expression or function in aortic VSMs. We found that α2C-ARs can be dramatically and selectively induced via a p38 MAPK-dependent pathway. Therefore, altered expression of α 2C-ARs may contribute to pathological changes in vascular function.
KW - BRL-44408
KW - Microcirculation
KW - MK-912
KW - p38 mitogen-activated protein kinase
UR - http://www.scopus.com/inward/record.url?scp=9144263607&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=9144263607&partnerID=8YFLogxK
M3 - Article
VL - 286
JO - American Journal of Physiology
JF - American Journal of Physiology
SN - 0363-6135
IS - 1 55-1
ER -